Process for preventing explosions in liquid-air apparatus



UNITED STATES.

PATENT OFFICE.

ROBERT GERARD AUBERT, F PARIS, FRANCE.

PROCESS FOR PREVENTING EXPLOSIONS IN LIQwD-AIR APPARATUS.

No Drawing. Application filed January 28, 1927, Serial No. 164,370, and in Germany August 15, 1925. y

In the commercial production of ex gen and nitrogen by the decomposition of liquid air, explosions sometimes occur inside the liquefying apparatus; and it has been ascertained, after much investigation, that such explosions are due to the presence in the air of combustible gases, principally acetylene. 'The said Combustible gases may be already contained in small quantities in the atmospheric air taken into the liquefying apparatus, or they may be formed by decomposition of lubricating oil in the air-compressor, the gaseous products thus entering into admixture with the air.

Said combustible gases collect in the vaporizer, forming explosive mixtures; and therefore explosions are liable to occur when these mixtures are brought into contact with the air in the oxygen zone of the separating apparatus.

With a view to preventing these damaging explosions, it has been proposed to take in the air in a condition as near as possible to absolute purity, by the use of high fines or air-ducts, reaching up to levels where impurities would be at a negligible minimum. But obviously this remedy is not everywhere possible of application; and particularly it is unavailable in industrial localities, since the air in such places is never pure. Moreover, even if atmospheric air could be always obtained chemically pure, it might 'become admixed with combustible gases generated, as already stated, from the lubricant used in the compressor.

The process, which is the subject of the present invention, is based upon the fact that certain combustible gases become solid at low temperatures at which air still remains liquid. Thus for example, acetylene becomes solid at '81.5 C. whilst air remains liquid at lower degrees of temperature.

Instead, therefore, of attempting to purify the air before it is liquefied, the com- 5 bustible gases therein, such as acetylene, (if any there be) are permitted to remain until the liquefaction of the air takes place, and until the acetylene is brought to a solid state at a temperature at which the air yet remains liquid; and the solidified gases are then separated (which can readily be done as by-filtration) before the mass comes into the oxygen zone of the apparatus.

This is, as is well known, the coldest part of the system; and by locating the filtering apparatus at that point it is possible to effect in a practical and successful manner the removal of the combustible gases, while in a solid state, from the liquid air before the separation of the oxygen from the nitrogen.

What is claimed is:

A process for preventing explosions in apparatus wherein oxygen and nitrogen are separately obtained in different zones by distillation of liquid air, which process consists in subjecting a volume of air containing an admixture of combustible gases such as acetylene to a temperature sufiiciently low to cause liquefaction of the air and solidification of said combustible gases, and separating the solidified combustible substances from the liquid air by filtration at the point in the system where the temperature is lowest, before the liquid air reaches the oxygen 7 zone of said apparatus.

In testimony whereof I have afiixed my signature.

ROBERT GERARD AUBERT. 

